1. Field of the Invention
The present invention relates to bituminous compositions and methods, and more specifically, relates to binders and methods for making the binders for bituminous compositions.
2. Background Information
Bituminous binders are used, particularly in the road construction industry, to provide bonding between aggregates or between a substrate and aggregates. The various possible uses are distinguishable by the following:                (i) The bituminous binder is hot-mixed with aggregates, and the resulting product is described as a hot bituminous mix. The bituminous binder provides the bonding between the aggregates.        (ii) The bituminous binder is hot-spread over a substrate, and the aggregates are spread over the bituminous layer which provides adhesion to the substrate. The resulting product is described as an anhydrous binder surfacing.        (iii) The bituminous binder is cold-mixed with aggregates and the resulting product is described as a cold bituminous mix produced with an aqueous bituminous product emulsion.        (iv) The bituminous binder is cold-spread, and the resulting product is described as a surfacing produced with an aqueous bituminous binder emulsion.        
When the mixes are prepared, or the spreading operations are carried out, it is always necessary for the consistency of the binder to be such that it allows good wetting of the aggregates, and for the consistency of the binder subsequently to change in order for the bituminous mixes or the surfacings thus produced to acquire mechanical performances which render them suitable for road construction use. A more fluid initial consistency of the binder is obtained either by heating the bituminous binder, or by thinning or fluxing (the two terms denote the same operation, the choice of one or the other usually being a function of the nature of the additive), by introducing a solvent or fluxing oil of petroleum or carbon chemistry origin, or by aqueous emulsification of the bituminous binder, or a combination of the above methods.
The solvents currently used are of petroleum or carbon chemistry origin. After the application of the binder, the solvents evaporate in order to allow the binder to recover its high consistency. The solvents, which are gradually dispersed into the atmosphere, pollute the atmosphere, contaminate aerobic organisms, and contribute to the greenhouse effect. Furthermore, the solvents generally comprise polycyclic aromatic compounds, at least some of which are recognized as mutagenic. The use of these solvents contributes to the exhaustion of fossil fuel resources. The presence of the above-mentioned solvents also poses safety problems, because they greatly lower the ignition point and require strict measures for protection against fire on storage and during transportation. French patent application FR 2768150 A1 (Saada) suggests using unsaturated fatty acid methyl esters as thinner components. These compounds, however, have been found to exhibit unsatisfying rheological behavior during the curing process.
The aim of the invention is to overcome all or part of the above disadvantages, without affecting the road construction performance of the bituminous binder or the conditions of use.